A Sunday walk gave James Watt the fix that launched the Industrial Revolution

Repairing a scale model of a Newcomen steam engine in 1765, Watt realized most of its power was wasted re-heating a cylinder that had just been cooled to condense steam. Walking across Glasgow Green, he hit on the fix: a separate condensing chamber that let the cylinder stay permanently hot, cutting fuel use dramatically and turning steam power from a curiosity into the engine of an era.

— William Rosen, The Most Powerful Idea in the World: A Story of Steam, Industry, and Invention — Random House, 2010
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